Successful recovery of highly viscous petroleum using a high-pressure thermal vapor stream typically involves production of hot combustion gases and steam that are flowed into a steam generating device to produce large quantities of high-pressure thermal vapor or steam. The high-pressure thermal vapor or steam is thereafter injected into a subsurface petroleum-bearing formation to facilitate extraction of the highly viscous petroleum therefrom. This recovery process is commonly referred to by those having ordinary skill in the art as “huff and puff,” steam flood, steam assisted gravity drainage (SAGD), and the like. Examples of apparatuses that may be used to produce a high-pressure thermal vapor stream are described in U.S. Pat. Nos. 4,156,421; 4,118,925; 3,980,137; 3,620,571; 2,916,877; 2,839,141; 2,793,497; 2,823,752; 2,734,578; 2,754,098; and 4,398,604; as well as Mexican Patents Nos. 105,472 and 106,801. Additionally, various methods for using such apparatuses are known in the art and include processes such as those disclosed in U.S. Pat. Nos. 3,993,135 and 3,948,323.
It is well known that in order to provide economical recovery of highly viscous petroleum, large volumes of thermal vapor must be generated and injected into the formation. This is particularly true, for example, where the thermal vapor is injected into the subsurface petroleum-bearing formation continuously over several hours, days, weeks, or even months. In addition, the thermal vapor must also be injected into the subsurface petroleum-bearing formation under pressures higher than the formation pressure in order for the thermal vapor to penetrate the formation. Moreover, certain highly viscous hydrocarbon deposits also require the application of large amounts of heat to reduce the viscosity and thus make recovery possible.
Because of the high volumes, pressures, and temperatures involved, difficulties often arise in obtaining, operating and maintaining the equipment and apparatuses needed for generating the required amounts of combustion gases that will produce the required amounts of steam under sufficiently high pressures and temperatures to provide satisfactory economic recovery of the highly viscous petroleum. For example, existing apparatuses that are capable of generating a suitable high-pressure thermal vapor stream tend to be large, heavy, and complex, and typically emit gases that are not environmentally friendly, all of which may result in additional costs to the petroleum recovery process. The environmentally harmful emissions from conventional equipment also make it difficult to use the high-pressure thermal vapor stream for other applications, such as cogeneration of electricity and heat.
Accordingly, what is needed is an improved apparatus and method for producing a high-pressure thermal vapor stream for injection into a subsurface petroleum-bearing formation to facilitate recovery of heavy viscous petroleum, for cogeneration of electricity and heat, and the like.